Serum neutralizing antibody titers in dairy cattle administered an inactivated vesicular stomatitis virus vaccine.

This research tested an inactivated vesicular stomatitis virus (VSV) vaccine on a dairy herd, measuring their serum neutralizing antibody titers over time. The results showed the vaccine elicited a strong initial immune response, which decreased significantly by 175 days post-vaccination, indicating a potential need for booster shots to maintain protection.

Research Methodology

• The research study was conducted on a dairy herd comprising 350 cows, both lactating and non-lactating.
• Each cow was administered two doses of an inactivated, formalin-killed, cell culture-derived VSV-New Jersey serotype vaccine intramuscularly.
• The vaccine doses were given 30 days apart.
• The researchers took serum samples from 96 cows before vaccination and again at 30, 52, and 80 days post-vaccination.
• A set of 24 cows from this group had samples taken 175 days post-vaccination.
• Additionally, 67 non-vaccinated heifers in the herd had their serum neutralizing antibody titers determined during the same period, serving as a control group.

Key Findings

• The peak group geometric mean serum neutralizing antibody titers, an indicator of the body’s immune response to the virus, was 1:530.46 +/- 1.14 (log10, 2.725 +/- 0.055). This peak occurred 21 days after the second vaccine dose.
• The serum neutralizing antibody titers decreased notably by 175 days post-vaccination, to 1:65.36 +/- 1.38 (log10, 1.815 +/- 0.142).
• Throughout the study, the non-vaccinated control group did not show any detectable antibody response to the VSV-New Jersey serotype.
• All serum specimens from the vaccinated group and the control group showed no reactivity to the VSV-Indiana serotype, indicating that the vaccine does not cross-protect against other VSV serotypes.

Implications

• The research shows that the inactivated VSV-New Jersey serotype vaccine elicits a significant initial neutralizing antibody response in dairy cows, demonstrating its effectiveness.
• However, the decreased antibody response over time necessitates further research into potential additional vaccine doses or booster shots to sustain immunity against the virus, particularly considering the role of dairy cattle in the virus’s epidemiology.
• The lack of cross-protection against other VSV serotypes also raises the question of whether separate or multi-serotype vaccines might be necessary in regions where other VSV types are prevalent.